Extraction method



Aug. 30, 1966 w. H. LYKKEN 3,269,657

EXTRACTION METHOD Original Filed April 29, 1963 5 Sheets-$heet 1 a 43 6i i INVENTOR. Wu. 1. MM H. L YKKEN W wmw A1- TQRNEYJ' 1966 w. H. LYKKEN3,269,667

EXTRACTION METHOD Original Filed April 29, 1963 5 Sheets-Sheet 2 58INVENTOR.

W/LL/A /i 1. YKKEN ATTORNEYJ Aug. 30, E966 w. H. LYKKEN 3,259,657

EXTRACTION METHOD Original Filed April 29, 1963 :5 Sheets-Sheet 5INVENTOR. VV/LLIAM/iLFK/(EN X/ Q M*M ATTORNEY! United States Patent3,269,667 EXTRACTION METHOD William H. Lykken, Springfield, Ohio,assignor to The Microcyclomat C0., Minneapolis, Minn, a corporation ofDelaware Original application Apr. 29, 1963, Ser. No. 276,457, nowPatent No. 3,221,998, dated Dec. 7, 1965. Divided and this applicationMar. 26, 1965, Ser. No. 462,462 2 Claims. (Cl. 241) This application isa division of application Serial No. 276,457, filed April 29, 1963, andnow Patent No. 3,221,- 998, issued December 7,1965.

This invention relates to a method for the separation and extraction ofsolid materials, such as the separation of asbestos fibers from asbestosbearing ores and extraction of gangue, and the like. Other exemplaryseparation and extraction processes include the extraction ofcontaminants from clay, talc, and similar non-metallic minerals for thepurpose of upgrading them.

The invention is illustrated in the accompanying drawings in which thesame numerals refer to corresponding parts and in which:

FIGURE 1 is a side elevation of apparatus for carrying out a separationand extraction process;

FIGURE 2 is a top plan of the same apparatus;

FIGURE 3 is an end elevation of the same apparatus;

FIGURE 4 is an elevation in section and on an enlarged scale through theapparatus and on the line 44 of FIGURE 2 and in the direction of thearrows;

FIGURE 5 is an end elevation of a modified form of apparatus; and,

FIGURE 6 is a partial plan view of the modified apparatus.

Referring to the drawings, the apparatus comprises a cylindrical casing10 housing means for reducing and dispersing the material to beseparated and extracted. Casing 10 is supported on a base 11 which alsosupports a motor 12 of sufiicient size and capacity to operate theapparatus. Conventional drive means, such as belts 13, connect the motorto the mechanism housed within casing 10. A feed hopper 14 is supportedon an arm 15 cantilevered out from the casing 10. Hopper 14 is connectedto the casing 10 by means of a tubular conduit 16 enclosing a helicalscrew feed 17. The screw feed 17 is driven by a separate electric motor18 through an appropriate drive enclosed within a safety housing 19.

Referring now to FIGURE 4, the apparatus includes a shaft 20 journaledin upper and lower bearings 21 and 22 for rotation about a vertical axiscentrally within casing 10. Bearing 22 is supported on the base 11. Oneend of shaft 20 extends through the bearing and base and is providedwith a multiple groove pulley 23 to adapt the shaft for rotation throughthe belt drive 13 from motor 12. Shaft 20 is provided with a keyway 24for attachment of rotor elements for rotation with the shaft.

The bottom most rotor element includes a hub 25 to which is attached anannular bottom plate 26 which carries a plurality of spaced radialblades 27 at its periphery. Plate 26 and radial blades 27 function as afan for drawing air through an annular opening 28 in the annular bottomplate 29 of casing 10 for the purpose of diluting and dispersing thematerial feed from hopper 14. Air inlet opening 28 is controlled by aplurality of slide dampers 30 for regulation of the volume of airadmitted.

Hub 25 supports a further annular plate 31 which carries a plurality ofspaced radial blades 32 at its periphery. Additional hubs 33 are mountedon the shaft 20. Each hub 33 supports an annular plate 31 carryingspaced radial blades 32. Each rotor stage represented by an annularplate 31 and series of radial blades 32 is separated from the adjacentstages by an annular disc 34 supported on the rotor shaft between thehubs.

As is well known in the art, the several rotor stages act upon thematerial fed into the lower portion of the casing 10 to reduce anddeagglomerate the solid material by air attrition and impact between theparticles and rotor blades and housing wall. At the same time, the solidmaterial is thoroughly diluted and dispersed in the air stream drawn inthrough the bottom air inlet. The material is acted upon in intrabladevortices between adjacent radial blades 32 spaced about the periphery ofthe rotor sections and in a rising vortex between the outer periphery ofthe rotor sections and the housing wall. The desired particles arephysically separated from any bonded impurities or contaminants. Thedesired particles are generally reduced in size. The impurities aregenerally more difficult to grind and thus are ground to a lesserextent.

The mixture of reduced and thoroughly dispersed solid material andseparated contaminants rises into the upper chamber 35 of the casing 10and into the cylindrical classifying or extracting casing 36 mounted ontop of the casing 10. A further hub 37 is positioned on shaft 20 forrotation therewith in cylindrical housing 36. Hub 37 is spaced from thereducing and dispersing rotor elements by means of a series of spacerrings or sleeves 38. Hub 37 supports a pair of annular plates 39 and 40held spaced apart by means of a spacer ring 41. A plurality offingerlike radiating blades or rods 42 are supported between plates 39and 40 at their outer periphery for rotation within cylindrical housing36.

A fan housing 43 is disposed on top of the apparatus above thecylindrical classification housing 36. An annular diaphragm ring 44 isdisposed between the classifier housing 36 and the fan housing 43. Anannular opening 45 defined by the inner periphery of diaphragm ring 44and the shaft hubs forms an opening communicating between the twohousings.

A fan hub 46 is secured to shaft 20 for rotation therewith within fanhousing 43. Hub 46 supports an annular plate 47 which in turn carries aplurality of spaced radial fan blades 48 at its outer periphery. Fanhousing 43 is in the form of an involute scroll as is conventional inthe art. The scroll housing terminates in a discharge port or conduit 49which leads to a collector for receiving the material discharged fromthe apparatus. The fan functions to induce a flow of air and materialthrough the apparatus and to discharge the lighter finer solid materials(which in most cases are the desired materials) separated from theoriginal feed.

In order to get from the top zone 35 of the material reducing anddispersing housing, the finer'and lighter material must first pass intoclassifier housing 36, where it is freed from the coarser and densermaterials, and must pass between the finger-like blades or rods 42 andbe drawn centripetally through the narrow passage 50 between the innerlip of diaphragm ring 44 and the outer lip of plate 40. The materialwhich makes its way through passage 50 is then caught up and entrainedin the stream of the fan blades and discharged out through conduit 49.

The coarser denser materials (which in most cases are the impurities orcontaminants) which are rejected by the classifier rotor, are throwncentrifugally outwardly to the cylindrical wall of housing 36 and arecaught by one of several coarse discharge or extraction conduits 51spaced about the wall of the classifier housing 36. One end of eachdischarge conduit 51 is in communication with a passage 52 in the wallof classifier housing 36. The opposite end of each discharge conduit 51is fitted with a flapper extraction valve 53.

Extraction valve 53 is composed of a resilient tube of rubber orsynthetic rubber-like resinous material. One

end is attached to conduit 51 by means of a clamp 54 or similarfastening device. The opposite end is flattened and is adapted tonormally remain closed. However, because of the resilience of thematerial of which the flapper valve is formed, the sides of the valvewhich are normally in face-to-face abutting position are forced apart bythe accumulation of coarse dense material in the valve 53 and dischargeconduit 51 so as to be discharged from the apparatus. The extractionvalve then closes automatically. In most instances the coarser densermaterial discharged through valve 53 is the unwanted material and isdiscarded after its discharge from the valve.

In FIGURES 5 and 6 there is shown an alternative form of apparatus inwhich the extractor or bleeder valve is replaced by a bleeder cyclone.The basic apparatus has substantially the same structure as that alreadydescribed except that a modified coarse discharge conduit 51A extendstangentially into the top cylindrical portion of a conventional uppercyclone 55. The lower conical portion of the upper cyclone 55 extendsinto the top wall of a lower cyclone 56. The bottom discharge end ofcyclone 56 is fitted with a gravity operated seal or valve 57. Valve 57includes a conduit having a diagonal opening against which is fitted aplate 58 hinged at 59 and having a threaded rod 60 extending out fromthe plate and fitted with an adjustable counterweight 61.

The extracted lcoarser and denser particles are separated from the airin the cyclones. The solid material passes downwardly through thecyclones and collects in the valve 57. When a sufiicient weight ofextracted particles collect in the valve to counterbalance the plate 58and its counterweight, the plate pivots on its hinge and opens theconduit to discharge the contents of the valve. The valve then closesautomatically due to the weight of the plate and counterweight.

The separated air and any fines entrained therein is desirably recycledthrough the apparatus. A conduit 62 extending from the top wall of theupper cyclone 55 is provided for this purpose. The conduit extends downto the base between the bottom of the reducing and dispersing rotor andthe base for reintroduction into the housing 10.

The apparatus of the present invention does two jobs simultaneously. Itprovides precise particle reduction and impurity extraction. Thecombined apparatus is a pulverizer-classifier including a heavy dutyhigh capacity air attrition mill with an integral classifier. It hasfound use in upgrading quality in many non-metallic mineral processingoperations where precisely controlled pulverization and positiveextraction of impurities are required. The present apparatus providesfor the sub-sieve size processing of filler clays, technical ceramics,lime, gypsum, rare earth oxides, pigments, asbestos, and similar friablematerials. It provides accurate control of particle reduction to anydesired average size from 150 microns to less than 1 micron. It providesfor the extraction of such impurities as silica, mica, sand iron etc.,which are usually found in non-metallic minerals. The effectiveextraction of impurities produced by this apparatus upgrades the productand reduces the cost of grinding.

The apparatus according to the present invention has been found to beespecially useful in increasing the rate of recovery of asbestos. In thepast, normal recovery of usable asbestos fiber from asbestos ore wasbetween 4% and 6%. The rest of the ore was discarded as tailings. -Bymeans of the present invention tailings piles are being reworked withsubstantially greater recovery of usable asbestos fiber than resultedfrom processing of the virgin ore. In the case of new ore, it is crushedto about inch mesh or finer before feeding to the apparatus. Millrejects and tailings may usually be fed directly.

Short asbestos fiber is used as a filler in plastic castings, asbestoscement, roofing cement, roof tile and Macadam road surfacing materialfor strength and improved wearability. Starting with raw rock or milltailings, recovery rates of acceptable short asbestos fibers have beenas high as 40% to 55% by weight of the feed material. Finished asbestosfiber produced by other extraction processes has been upgraded by meansof the present invention by opening the fiber bundles to release trappedrock and iron to extract and discharge the same. With such finishedfiber starting material, recovery rates have been as high as 88% to 97%.

Clay occurs in huge natural deposits, generally in very fine particlesizes in the range of 2 microns and finer. Clay normally containsrelatively small amounts (about 2% to 3%) of impurities in the form ofmica flakes, silica and silicates, traces of iron, etc. For many usesthe presence of these impurities may not be objectionable. However,where the end use requires a very white color, as in the preparation ofpaper coatings, fine china and the like, the presence of even 2% to 4%impurities downgrade the product. By passing such clay through theapparatus of the present invention and extracting only 3% to 4% of thetotal clay feed, enough of the impurities are removed to raise the colorof the remaining material 2 to 3 points on the General Electric ColorTester.

Using a 30 inch diameter mill of 100 horsepower, the capacity of themill is 4,000 pounds of clay per hour. Because the impurities are merelyextracted, instead of being ground, this rate of production can bemaintained. If it were necessary to grind the 2% to 3% impuritiespresent, the production would have to be cut to 1,000 pounds per hour orless. The wear on the machine would be increased and the color of thefinished product would be lower because impurities would still bepresent although in smaller size.

Tale is upgraded in much the same manner as clay. It occurs naturally inlarge deposits and contains small amounts of oversize impurities. Gypsumhas similarly been upgraded by extracting dolomite. Substantialquantities of gypsum have been recovered from mill rejects. Cocoacontains about 2% to 3% fiber which is hard to grind and adds nothingbut bulk and weight to the product. By removing this 2% to 3% of fiberby the extraction process according to the present invention, grindingproduction of cocoa can be doubled.

It is apparent that many modifications and variations of this inventionas hereinbefore set forth may be made Without departing from the spiritand scope thereof. The specific embodiments described are given by wayof example only and the invention is limited only by the terms of theappended claims.

I claim:

1. A method of upgrading the quality of non-metallic solid materials bythe separation and extraction therefrom of coarse and dense impuritiesand contaminants which are more ditficult to grind than the solidmaterials containing the impurities and contaminants, said methodcomprising introducing said impure and contaminated solid material intothe side of a vertically disposed relatively narrow cylindrical annulargrinding and dispersing zone adjacent the bottom end thereof, entrainingsaid impure and contaminated solid material in an air stream in a risingvortex in said zone, subjecting said impure and contaminated material inits ascent in said vortex simultaneously to air attrition in a pluralityof stacked smaller vortices spaced around the inner periphery of saidzone to reduce said impure and contaminated solid material and tophysically separate contained impurities and contaminants from saidsolid material, further dispersing said separated solid material andimpurities and contaminants in air by releasing the same upwardly intoan immediately adjacent open cylindrical expansion zone, passing theresulting dispersed mixture of separated solid material and impuritiesand contaminants upwardly into a cylindrical classification zone,subjecting the mixture of separated solid material and impurities andcontaminants in that Zone to opposed centripetal and centrifugal forceswhereby coarser and denser impure and contaminating particles are throwncentrifugally outwardly and extracted from the mixture and the finer andlighter particles of solid material freed from extracted impurities andcontaminants are drawn centripetally inwardly and upwardly anddischarged to a recovery zone.

2. A method according to claim 1 further characterized in thatnon-metaallic solid materials selected from the class consisting ofasbestos, clay, talc, gypsum and cocoa are upgraded by the extractionfrom said solid materials of impurities and contaminants selected fromthe class consisting of mica, silica, silicates, iron, dolomite andfiber.

References Cited by the Examiner UNITED STATES PATENTS Lykken 24156 XLykken, 241-56 X Lecher 2411 Adorno 241-4 X Lykken 24l-56 X Jackering241--53 Brown et al. 241-14 X ROBERT C. RIORDAN, Primary Examiner.

H. F. PEPPER, Assistant Examiner.

1. A METHOD OF UPGRADING THE QUALITY OF NON-METALLIC SOLID MATERIALS BYTHE SEPARATION AND EXTRACTION THEREFROM OF COARSE AND DENSE IMPURITIESAND COMTAMINANTS WHICH ARE MORE DIFFICULT TO GRIND THAN THE SOLIDMATERIALS CONTAINING THE IMPURITIES AND CONTAMINANTS, SAID METHODCOMPRISING INTRODUCING SAID IMPURE AND CONTAMINATED SOLID MATERIAL INTOTHE SIDE OF A VERTICALLY DISPOSED RELATIVELY NARROW CYLINDRICAL ANNULARGRINDING AND DISPERSING ZONE ADJACENT THE BOTTOM END THEREOF, ENTRAININGSAID IMPURE AND CONTAMINATED SOLID MATERIAL IN AN AIR STREAM IN A RISINGVORTEX IN SAID ZONE, SUBJECTING SAID IMPURE AND CONTAMINATED MATERIAL INITS ASCENT IN SAID VORTEX SIMULTANEOUSLY TO AIR ATTRITION IN A PLURALITYOF STACKED SMALLER VORTICES SPACED AROUND THE INNER PERIPHERY OF SAIDZONE TO REDUCE SAID IMPURE AND CONTAMINATED SOLID MATERIAL AND TOPHYSICALLY SEPARATE CONTAINED IMPURTIES AND CONTAMINANTS FROM SAID SOLIDMATERIAL, FURTHER DISPERSING SAID